From 01df00fd0f509c486a84d9e5ec6a006708955bd9 Mon Sep 17 00:00:00 2001
From: Todd Treece <360020+toddtreece@users.noreply.github.com>
Date: Tue, 22 Feb 2022 22:17:35 -0500
Subject: [PATCH] DataFrame: Add cached response notice for X-Cache: HIT header
 (#45564)

---
 .../src/utils/queryResponse.test.ts           | 51 ++++++++++++++++++-
 .../src/utils/queryResponse.ts                | 31 ++++++++++-
 2 files changed, 80 insertions(+), 2 deletions(-)

diff --git a/packages/grafana-runtime/src/utils/queryResponse.test.ts b/packages/grafana-runtime/src/utils/queryResponse.test.ts
index 0f64a32a1bd..36bdcdf953e 100644
--- a/packages/grafana-runtime/src/utils/queryResponse.test.ts
+++ b/packages/grafana-runtime/src/utils/queryResponse.test.ts
@@ -1,6 +1,6 @@
 import { DataQuery, toDataFrameDTO, DataFrame } from '@grafana/data';
 import { FetchError, FetchResponse } from 'src/services';
-import { BackendDataSourceResponse, toDataQueryResponse, toTestingStatus } from './queryResponse';
+import { BackendDataSourceResponse, cachedResponseNotice, toDataQueryResponse, toTestingStatus } from './queryResponse';
 
 const resp = {
   data: {
@@ -277,6 +277,55 @@ describe('Query Response parser', () => {
     expect(ids).toEqual(['A', 'B']);
   });
 
+  describe('Cache notice', () => {
+    let resp: any;
+
+    beforeEach(() => {
+      resp = {
+        url: '',
+        type: 'basic',
+        config: { url: '' },
+        status: 200,
+        statusText: 'OK',
+        ok: true,
+        redirected: false,
+        headers: new Headers(),
+        data: {
+          results: {
+            A: { frames: [{ schema: { fields: [] } }] },
+          },
+        },
+      };
+    });
+
+    test('adds notice for responses with X-Cache: HIT header', () => {
+      const queries: DataQuery[] = [{ refId: 'A' }];
+      resp.headers.set('X-Cache', 'HIT');
+      expect(toDataQueryResponse(resp, queries).data[0].meta.notices).toStrictEqual([cachedResponseNotice]);
+    });
+
+    test('does not remove existing notices', () => {
+      const queries: DataQuery[] = [{ refId: 'A' }];
+      resp.headers.set('X-Cache', 'HIT');
+      resp.data.results.A.frames[0].schema.meta = { notices: [{ severity: 'info', text: 'Example' }] };
+      expect(toDataQueryResponse(resp, queries).data[0].meta.notices).toStrictEqual([
+        { severity: 'info', text: 'Example' },
+        cachedResponseNotice,
+      ]);
+    });
+
+    test('does not add notice for responses with X-Cache: MISS header', () => {
+      const queries: DataQuery[] = [{ refId: 'A' }];
+      resp.headers.set('X-Cache', 'MISS');
+      expect(toDataQueryResponse(resp, queries).data[0].meta?.notices).toBeUndefined();
+    });
+
+    test('does not add notice for responses without X-Cache header', () => {
+      const queries: DataQuery[] = [{ refId: 'A' }];
+      expect(toDataQueryResponse(resp, queries).data[0].meta?.notices).toBeUndefined();
+    });
+  });
+
   test('resultWithError', () => {
     // Generated from:
     // qdr.Responses[q.GetRefID()] = backend.DataResponse{
diff --git a/packages/grafana-runtime/src/utils/queryResponse.ts b/packages/grafana-runtime/src/utils/queryResponse.ts
index 55c12a20703..748efa4d57d 100644
--- a/packages/grafana-runtime/src/utils/queryResponse.ts
+++ b/packages/grafana-runtime/src/utils/queryResponse.ts
@@ -12,10 +12,13 @@ import {
   DataQuery,
   DataFrameJSON,
   dataFrameFromJSON,
+  QueryResultMetaNotice,
 } from '@grafana/data';
 import { FetchError, FetchResponse } from '../services';
 import { toDataQueryError } from './toDataQueryError';
 
+export const cachedResponseNotice: QueryResultMetaNotice = { severity: 'info', text: 'Cached response' };
+
 /**
  * Single response object from a backend data source. Properties are optional but response should contain at least
  * an error or a some data (but can contain both). Main way to send data is with dataframes attribute as series and
@@ -62,6 +65,7 @@ export function toDataQueryResponse(
   if ((res as FetchResponse).data?.results) {
     const results = (res as FetchResponse).data.results;
     const refIDs = queries?.length ? queries.map((q) => q.refId) : Object.keys(results);
+    const cachedResponse = isCachedResponse(res as FetchResponse);
     const data: DataResponse[] = [];
 
     for (const refId of refIDs) {
@@ -85,7 +89,10 @@ export function toDataQueryResponse(
       }
 
       if (dr.frames?.length) {
-        for (const js of dr.frames) {
+        for (let js of dr.frames) {
+          if (cachedResponse) {
+            js = addCacheNotice(js);
+          }
           const df = dataFrameFromJSON(js);
           if (!df.refId) {
             df.refId = dr.refId;
@@ -128,6 +135,28 @@ export function toDataQueryResponse(
   return rsp;
 }
 
+function isCachedResponse(res: FetchResponse<BackendDataSourceResponse | undefined>): boolean {
+  const headers = res?.headers;
+  if (!headers || !headers.get) {
+    return false;
+  }
+  return headers.get('X-Cache') === 'HIT';
+}
+
+function addCacheNotice(frame: DataFrameJSON): DataFrameJSON {
+  return {
+    ...frame,
+    schema: {
+      ...frame.schema,
+      fields: [...(frame.schema?.fields ?? [])],
+      meta: {
+        ...frame.schema?.meta,
+        notices: [...(frame.schema?.meta?.notices ?? []), cachedResponseNotice],
+      },
+    },
+  };
+}
+
 /**
  * Data sources using api/ds/query to test data sources can use this function to
  * handle errors and convert them to TestingStatus object.